Fornia



L. F. FULLER.

RADIOTELEGRAPHY.

APPLICATION FILED AUG-30, ms.

1,358,143, Patented Nov. 9, 1920.

fi/J A TTORNE YS ,UNITED STATES PATENT OFFlCE- LEONARD r. FULLER, or PA O ALTO, CALIFORNIA, ssronon TO FEDERAL TELE- own company, or SAN FRANCISCO, CALIFORNIA, A CORPORATION 01* CALI- RADIOT LE RAPHY.

' Specification of Letters Patent.

Patented Nov. 9, 1920.

, Application filed August 80, 1918. Serial No. 252,033.

7 0 all whom it may concern:

Be it known that I, LEONARD F. FULLER, a

- citizen of the United States, anda resident of Palo Alto, county of Santa Clara, and

tion. r v y The invention relates to a transmission system of radiotelegraphy and particularly continuous-oscillation radiotelegraphy, in-

. volving variations in antenna inductance.

In my copending application, Serial No. 192,209, filed in the United States Patent Ofiice on September 19, 1917, I have shown a radiotelegraphy transmission system, involving an antenna loading coil and a loop circuit inductively connected thereto, which t loop isopened and closed to vary the inductance of the antenna circuit for signaling purposes. The loop circuit was divided into i a plurality of segments, preferably of equal length by radial conductors, connected at one end to the loop at equally spaced points and connected together attheirother ends. at the center of the circle of the loop. A switch was arranged in eachsegment of the loopandmeans were provided for opening or closing all of the switches substantially simultaneously, butin practice I have found that all of the switches are not opened at the same time. p

Each radial conductor formed a common side to two adjacent sectors and consequently the mutual inductance between adjacent sectors was high. Since the switches do not all open at the same time, the switch which opens first, would, at the start of its opening, have to break the current circulating in the loop and would have across its contacts, the voltage of its sector. If there were ten sectors. this voltage should be one-tenth of the total reactive drop of the current through the circular loop. During the period that the switch opened, less and less current would flow through the. key contacts and more and more of the loop current wouldbe forced through the radials of the sector that was being opened, until finally, when the switch was wide open. no current would. flow through the switch contacts and the total remainingloop current would flow down one radial to the center and up the other, thus shunting by the open key. Due to this fact,

the flux through the area of the open sector due to the current in the radials, causes a greater voltage across the switch contacts,

than one-tenth of the total loop Volta e, because this flux is in phase with the the main loading coil. The main loading coil flux links all sectors equally and when the switches start to open, the flux density in all of the sectors is equal, but asone switch opens, the flux through the opening sector is increased, producing a greater voltage across the switch contacts.

For example, if the loop radial system shown in the application mentioned above had to open a circuit of one hundred kilovolt-amperes, and there were ten sectors, experiments have shown that that the first switch to open would have to open aboutseventeen kilo-.volt-amperes, an increase of 70% over the normal ten kilo-volt-amperes, and

that the last switch of the ten would be 0 erating at about five kilo-volt-amperes. his reduces the efficiency of the former system, since it is necessary to employ more switches and sectors, than if an equal number of kilovolt-amperes were opened by each switch.

This presents a deleterious feature which it is an object of the present invention to overcome.

Another object of the present invention is to provide means for emitting wave trains at a definite group frequency from an arc transmitting station.

The invention possesses other advantageous features, some of which, with the foregoing, will be set forth at length in the following description where I shall outline in full, that form of the invention which I-have selected for illustration in the drawings accompanying and forming part of the present specification. In said drawings I have shown one specific form of the system of my invention, but itis to be understood that I do not limit myself to such form, since the invention, as expressed in the claims, may be embodied in a plurality of forms.

Referring to said drawings: Figure 1 is a diagrammatic representation of a radiotelegraphy transmission system embodying my invention.

Fig. 2 is a'diagrammatic representation of the loop circuit of my invention. The ordinary continuous oscillation transmission system may be represented by an are 2 supplied with current from the genei One side of the arc is grounded and the other side is connected to the antenna :l, tl much the Variable inductance or loading coil 5 Arranged in inductive relation with the loading coil 5 and preferably dire 'y below the lower turn there-or are a i .ralm' cl:

separate isolated sectors 6, the cuter or are shaped conductors let each sector lying in a circle, preferably of substantially the same diameter as the loading coil. The raz lial conductors 8 of the sectors are s aced from each other circumiterentially, so l tual inductance between adjacent sectors is low, thereby obviating the diliiculties of the former system, and the greater the s, inn between the radial conductors S, the less wi fl be the mutual inductance and the will he the elliciency the system.

Arranged in each sector and or: the are shaped conductor 7 of Q a switch or relay 9, the re so that they may be oper ays are connected in series in the local circuit with the key 15.

In the present construction, with tual inductance between the s ctois. 7 possible to load each relay to its full value, since regardl ss of the sequence c opening of the sectors, each relay will its full load and no more, thereby r du the number of relays from those recurire the former system. 7

This system a geously to the em; from an arc transmitting st:

u ,c li hen it is desirable to produce a tone iii hey, for example a live hundred cycle note, i connect choppers or motor operat c i mutat vices 1st around each pair c ilay cout' c in series with each pair desired. These chopper together and it .is tl'ierelfore desiruh I .1? they be all arranged on the same s ur no operated together so that they all lllz'lh'IQ and lit" iiystem rit, a 0

in said circuit, a plurality of isolated circuits arranged in the same inductive relation to said loading coil whereby a relatively sir i current is induced in each isolated circuit and means for opening and closing said cirouits.

l. A radiotelegraphy transmission system ii'icluding an antenna circuit, a loading: coil. in said circuit, a plurality oi spaced conductors arranged adjacent to said coil and. concentric to the axis thereoil', conducto s arranged within said concentric cou urtos and forming with the concentric co uctors a plurality of isolated circuits and means for opening" and closing said circuits.

5. A radiotelcgraphy transmission sv iiurliuling an antenna circuit, a loadi in said circuit, a pliu'ality of s; aced tors arranged adjacent to said co' co tric to the axis thereof, condi nected to the ends of said spaced team, and extending toward szid fs and circuits with said spaced conduct means for openingand closing said circuits-;.

6. A radiotelegraphy transmission system including an antenna circuit, a loadin coil in said circuit a plurality of sector (are. having low mutual induc vaucc, inducti. connected to said loading coil 1d means opening; and closing the sect circi'iits.

7. A radiotelegraphy trai IllSlOll s including an antenna circuit,

i 1 :1 loading: coil u said circuit, a plurality oi sector circuits inductively connected to s, leading coil, means for opening and cloe the circuits and means for interrup o the se tor circuits at a tone frequency 8. A radiotelegraphy transn on s s wtezu ,iucliding an antenna circuit, a sling;- coil in said circuit, a plurality oi": isolatcril circuits arranged in the same inductive relation to said loading coil, means for opening" the i tolatwl circuits and means for regularly cloua and opening the isolated circuits at a tone frequency.

9. A radiotelegraphy transmission system including an antenna circuit, a loading coil in said circuit, a plurality of isolated sector circuits inductively connected to said leading coil, a switch. in each sector circuit and a chopper connected. across each su. iii.

10. A radiotelegraphy transmission systern, including! an antenna circuit, a leading; coil in said circuit, a plurality oi circuits arranged in the same inductive relation to. said loading coil and means for opening and closing said last named circuits at a tone freeuency.

In testimony whereof, I l are hereunto set my hand at Palo Alto, Cal fornia, this st day of August, 1918.

LEONARD F. FULLER. 

